Abstract
A Micro Heat Exchanger (MHE) can effectively control the temperature of surfaces in high heat flux applications. In this study, several turbulence models are analyzed using a 3-D finite element model of a MHE. The MHE consists of a narrow planar flow passage between flat parallel plates with small cylindrical pin fins spanning these walls. The pin fin array geometry investigated is staggered, with pin diameter of 8.46 mm, height to diameter ratio of 1.0 and streamwise (longitudinal) and spanwise (transverse) to diameter ratios of 1.5 and 2.5, respectively. Pressure loss and heat transfer simulated results for 4,000≤Re≤50,000 are reported and compared with previously published numerical and experimental results. An overall thermal performance parameter is defined in terms of both the Nusselt number and the friction factor, in order to investigate the performance of the MHE at different Reynolds numbers. It was found that the flat micro pin fin overall thermal performance exceeded the parallel plate counterpart (smooth channel) by a factor of 1.2 to 2.2 in the investigated Reynolds number range. Moreover, among the six turbulence models investigated, the RNG model tends to be the best model to predict both the Nusselt number and the friction factor and capture the main feature of the flow field in MHE.
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